Specimen positioning device for electron microscope and the like

ABSTRACT

A specimen positioning device for an electron microscope or the like is provided which comprises a rectilinear motion mechanism and a rotating mechanism. A movable member in the rectilinear motion mechanism and a rotary member in the rotating mechanism are selectively coupled under the Coulomb force to a driven member which carries a specimen holder, so that the rectilinear or rotary motion may be transmitted to a specimen.

United States Patent 1 Sakitani SPECIMEN POSITIONING DEVICE FOR ELECTRONMICROSCOPE AND THE LIKE [75] Inventor: Yoshio Sakitani, Katsuta-shi,Japan [73] Assignee: Hitachi, Ltd., Tokyo, Japan [22] Filed: Aug. 24,1972 [21] App]. No.: 283,294

[30] Foreign Application Priority Data Aug. 25, 197] Japan .46/64441 52us. (:1 .Q 250 495 B [51] Int. Cl. HOlj 37/20 [58] Field of Search250/495 B [56] Y i References Cited UNITED STATES PATENTS 3,628,01312/1971 Heide 250/495 B 3,678,270

7/1972 Braun 250/495 B [111 3,745,341 [451 July 10,1973

Primary Examiner-Archie R. Borchelt Assistant Examiner-C. E. ChurchAttorney-Paul M. Craig, Jr., Donald R. Antonelli et a1.

[5 7] ABSTRACT A specimen positioning device for an electron microscopeor the like is provided which comprises a rectilinear motion mechanismand a rotating mechanism. A movable member in the rectilinear motionmechanism and a rotary member in the rotating mechanism are selectivelycoupled under the Coulomb force to a driven member which carries aspecimen holder, so that the rectilinear or rotary motion may betransmitted to a specimen.

3 Claims, 4 Drawing Figures Patented July 10, 1973 5 Sheets-Sheet 1 F/GnPatented July 10, 1973 3,745,341

3 Sheets-Sneet 2'3 Patented Jul 10, 1973 3,745,341

3 Sheets-Snet :5

SPECIMEN POSITIONING DEVICE FOR ELECTRON MICROSCOPE AND THE LIKEBACKGROUND OF THE INVENTION In the prior art a specimen positioningdevice used in an electron microscope generally comprises a compoundmechanism for imparting the rectilinear motion and rotation to aspecimen. The rectilinear motion mechanism and the tilting mechanism aremounted upon the rotating mechanism or the rotating and tiltingmechanisms are mounted on the rectilinear motion mechanism. Thereforce,the prior art specimen positioning devices have distinct defect that theaxis of rotation or tilting of the specimen is displaced when therectiliniear movement and tilting of the specimen are displaced when thespecimen is rotated. Since various mechanisms such as universal joints,strings and the like are used in order to transmit the motions to themechanisms mounted on the other mechanism, the prior art specimenpositioning devices have defects that they are large in size and thatthe range within which the specimen may be moved is limited.

SUMMARY OF THE INVENTION The present invention has for its object toprovide a specimen positioning device for an electron microscope and thelike which may selectively impart to a specimen a rectilinear motion, arotary motion or tilting motion and which is very simple in constructionand compact in size.

Briefly stated, the present invention is characterized by the provisionof means for selectively coupling a rectilinear motion mechanism and arotating mechanism to a specimen holder through Coulomb electrostaticattraction, and means for rotating both said rectilinear motionmechanism and said rotating mechanism in unison with each other.

The above and other objects, features, and advantages of the presentinvention will become more apparent from the following description ofthe preferred embodiments thereof taken in conjunction with theaccompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a sectional view of a priorart specimen positioning device;

FIG. 2 is a perspective view of another prior art specimen positioningdevice;

FIG. 3 is a sectional view of a first embodiment of the presentinvention in which a specimen positioning device is used as a specimenfine adjustment of an electron microscope; and g FIG.'4 is alongitudinal sectional view of a second embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of thepreferred embodiments of the present invention, the prior art specimenpositioning devices will be briefly described with reference to FIGS. 1and 2 in order to distinctly point out the problems and defectsencountered in the prior art devices.

First referring to FIG. 1 illustrating the prior art spec imenpositioning device of the type in which both a specimen and a fineadjustment may be simultaneously replaced, a compound fine adjustmentproper 41 is placed in a magnetic path 37 with a pivot pin 34, a pivotbearing 39, a spring 40 and a ball joint 52 with 0- rings 53 and 54. Asthe fine adjustment proper 41 is moved into and out of the magnetic path37 through the ball joint 52, the fine translation of a specimen 44 maybe effected in the direction indicated by the double-pointed arrow X.When the fine adjustment proper 41 together with the ball joint 52 isswung in the direction indicated by the double-pointed arrow Y, a substantially rectilinear fine movement of the specimen 44 may be effectedin the direction Y. When the fine adjustment proper 41 is rotated in theball joint 52 in the direction indicated by the double-pointed arrow T,a fine tilting movement of the specimen 44 may be effected. When arotary table or stage 43 upon which is mounted the specimen 44 isrotated from the exterior, the rotation of the specimen 44 may beeffected.

Next the mechanism for rotating the specimen 44 will be described indetail hereinafter. The rotary table 43 is rotatably fixed to the fineadjustment proper 4K in such a manner that the specimen 44 may be placedsubstantially at the center of the magnetic path 37. A drum 49 isrotatably mounted on a stationary table 91 of the fine adjustment proper4ll extended outwardly of the magnetic path 37. A string 46 whose bothends are fixed to pins 46 and positioned at both ends of the stationarytable 91, is wrapped around the rotary table 43, a pin 42 extending fromthe end close to the pivot 38 of the fine adjustment proper 41, and thedrum 49. The drum 49 is normally so biased as to move away from therotary table 43 through a :sliding bearing mem ber 48 under the force ofa tension spring 47 loaded in a guide groove 92 of the fine adjustmentproper 44 so that the string 45 may be always imparted with a uniformtension, thereby producing the frictional force between the string 45and the rotary table 43. A fine adjustment rod 51 is moved in thedirection indicated by the arrow R so that the string 45 is movedagainst the tension spring 47 thereby causing the rotary table 43 andhence the specimen 44 in the direction indicated by the arrow R.

In summary, the specimen 44 is rectilinearly translated in the X and Ydirections with respect to the magnetic path 37, is tilted in thedirection T and is rotated in the direction R.

Next referring to FIG. 2, another prior art specimen positioning devicewill be described in which only the specimen 3 upon a specimen holder 4may be replaced.

A fine moving plate 1 is located in the magnetic path with respect to alens 2 and is translated in the X and Y direction by a spring l3, andfine adjustment rods l l and 12. Means are provided on the plate 4 fortilting and rotating the specimen 3.

The rotation of a tilting shaft 117 is transmitted to a tilting table 5through a universal joint 16, a worm 8, a gear 20 and a slide 24.disposed on the plate ll, thereby tilting the specimen 3. The fineadjustment in a tilted plate of the specimen supporting tube 4 is madeby a fine adjustment table 6 which is disposed on the tilting table 5and to which is transmitted the rotation of a rotary shaft 19 through auniversal joint 14, a worm W and a spring 22. Upon the adjustment plate6 is disposed a rotary table 7 provided with a bevel gear for supportingthe specimen supporting tube 4. The rotation of the rotary shaft 18 istransmitted to the rotary table 7 and hence the specimen 3 through auniversal joint and a bevel gear 9 in mesh with the bevel gear of therotary table 7.

In summary, the second prior art specimen positioning device is of theso-called stacking type in which the rectilinear motion mechanism, thetilting mechanism and the rotating mechanism are stacked in the ordernamed.

THE INVENTION, FIGS. 3 AND 4 The specimen positioning device inaccordance with the present invention shown in FIG. 3 may selectivelytranslate and rotate a specimen. The speciment positioning device isdisposed in an opening 23' of a supporting member 23 made of anelectrically insulating material. A specimen holder 26 adapted to hold aspecimen 27 is fitted into a center opening of a metallic driven disk 33which is interposed between a pair of upper and lower metallic disks 24and 30. Thin disks 28 and 32 made of a semiconductive ferroelectricmaterial with a specific volume resistivity ranging from to 10 ohm-cmare bonded to the metallic disks 24 and 30 respectively withelectrically conductive adhesive 25 and 31. The driven disk 33 and thedisks 24 and 30 are coupled to a voltage source 93 through lead wires94, 95, and 96 respectively so that the same voltage may be impressedbetween the disk 24 and the driven disk 33 and between the disk 30 andthe driven disk 33. A switch 36 is inserted between the voltage source93 and the lead wires 95 and 96 so one of the pair of disk 24 and 30 maybe selectively coupled to the voltage source 93.

The thin disks 28 and 32, the disks 24 and 30 are provided with centeropenings 28', 32, 24 and 30', respectively which are in line with oneanother when assembled. The diameters of these openings 28', 32, 24' and30' are so selected that the specimen holder 26 may move in a planewithin these openings.

The flange of the upper disk 24, which is the fine adjustment disk, isfitted into an annular groove 97 formed in the inner wall of the opening23' of the supporting member 23. The flange of the lower disk 30, whichis the rotary disk, is placed upon an annular stepped portion 98 formedin the opening 23 of the supporting member 23.

The rectilinear translation of the fine adjustment disk 24 may beeffected by a pair of fine adjustment rods 34 and 35 whereas therotation of the rotary disk 30 may be effected by a rotary driving shaft29' which carries a driving gear 29 in mesh with a pinion or driven gear99. mounted upon the undersurface'of the rotary disk 30.

Next the mode of operation will be described. The movable contact of theswitch 36 is made into contact with the fixed contact connected to thelead wire 95 so that the d-c voltageranging from 200 to 700 volts isimpressed between the rotary disk 30 and the driven disk 33 so that thedriven disk 33 may rotate in unison with the rotary disk 30 through theCoulomb electrostatic attraction whereas the driven disk 33 isoperatively disconnected from the fine adjustment disk 24. Next therotary disk 30 is rotated by the rotary shaft 29' through the gear 29and the pinion 99, thereby adjusting the angular position of thespecimen holder 26 and hence the specimen 27.

In order to adjust the position of the specimen 27 by the rectilinearmovement, the movable contact of the switch 36 is made into contact withthe fixed contact connected to the lead wire 96 so the d-c voltage maybe applied between the fine adjustment disk 24 and the driven disk 33,thereby causing the latter to move in unison with the fine adjustment 24while operatively disconnecting the driven disk 33 from the rotary disk30. When the fine adjustment rods 34 and 35 are actuated, the fineadjustment disk 24 is caused to make a rectilinear movement, therebyreciprocating the specimen holder 26 in a plane. Thus the fineadjustment of the specimen 27 in the lateral direction may beaccomplished.

Next the second embodiment of the present invention will be describedhereinafter with reference to FIG. 4. The second embodiment is differentfrom the first embodiment in that it further comprises a mechanism fortilting the specimen.

The specimen positioning device together with the specimen 59 isdirectly inserted into a space of a lens 56 held in position'by a lensholder 78 at the center of a magnetic path 55. The specimen positioningdevice generally comprises an insulator 57, a holder 8 and a sealedblock 71. At one end of the insulator 57 is disposed a specimen fineadjustment mechanism comprising a driven disk 64 carrying a specimenholder 58 which in turns holds the specimen 59, a rotary disk 61, a fineadjustment disk 60, and a retainer 77. The driven disk 64 is interposedbetween the rotary disk 61 and the fine adjustment disk 60. Disks 63 and62 made of a semiconductive ferroelectric material are bonded to therotary disk 61 and the fine adjustment disk 60, respectively, withelectrically conductive adhesives 85 and 86. The rotary disk 61 isrotated about the axis of the lens 56 through a gear 84, a rotary shaft65, a spring 67 and a vacuum proof rotating shaft 70. The rectilineartranslation of the fine adjustment disk 60 may be effected by amechanism comprising a spring 72 which is coupled to a pin 83 extendingfrom the fine adjust ment disk 60 with a string 82, a guide plate 74, aconnecting rod 68 and a fine adjustment rod 69. The specimen holder 58,the specimen 59 and the driven disk 64 are electrically grounded througha lead wire 76, a contact 75 and the magnetic path 55, and the rotarydisk 61 and the fine adjustment disk 60 are connected to a switch 81through lead wires 66 and 73, respectively.

Next the mode of operation will be described. The switch 81 is soswitched that the d-c voltage ranging from 200V to 700V from a voltagesource 89 is applied between the fine adjustment disk 60 and the drivendisk 64 so that the great Coulomb electrostatic attraction produced inthe contact surface between the driven disk 64 and .the semiconductiveferroelectric disk 62 serves to cause the driven disk 64 to move inunison with the fine adjustment disk 60. Therefore, the rectilineartranslation ofthe specimen 59 may be effected through the fineadjustment rod 69, th connecting rod 68 and the guide plate 74. Next theswitch 81 is so switched that the d-c voltage is applied between thedriven disk 64 and the rotary disk 61 so that the Coulomb electrostaticattraction produced in the contact surface between the driven disk 64and the semiconductive ferroelectric disk 61 serves to cause the drivendisk 64 to move in unison with the rotary disk 61. Therefore, thespecimen 59 is rotated about the axis of the lens 56 by the rotatingmechanism'comprising the vacuum proof rotating shaft 70, the spring 67,the rotary shaft 65 and the gear 84, independently of the rectilinearmovement described above.

When it is desired to tilt the specimen 59, the specimen positioningdevice may be tilted by a knob 87 formed at the outer end of the block71.

From the foregoing description, it is seen that according to the presentinvention, the positioning mechanisms may be individually actuated todetermine the position of the specimen. The mechanisms for transmittingthe motion to the specimen does not include universal joints, drums andstrings so that the specimen positioning device may be made compact insize and that the specimen positioning range may be increased.

When the specimen positioning device in accordance with the presentinvention is used in an electron microscope, the position of a specimenmay be adjusted in a reference plane so that the image with a higherdegree of accuracy may be formed. Furthermore the specimen holder iselectrically grounded so that the effects upon the electrostatic lens bythe driving mechanisms due to the electron beams may be prevented.

What is claimed is. t

l. A specimen positioning device for an electron microscope or the likecomprising a. means for supporting a specimen;

b. a driven member into a center opening of which is fitted saidspecimen supporting means;

0. a rectilinear motion imparting member disposed in closely spacedapart relation with said driven member on one side thereof;

d. a rotary 'motion imparting member disposed in closely spaced apartrelation with said driven'member on the other side thereof;

e. means drivingly coupled to said rectilinear motion imparting memberfor causing the fine motion thereof;

f. means drivingly coupled to said rotary motion imparting member forcausing the rotation thereof; and

g. a voltage source one terminal of which is connected to said drivenmember and the other terminal of which is selectively connected througha switch to either of said rectilinear motion imparting mechanism orsaid rotary motion imparting mechanism so that Coulomb electrostaticattraction is produced between said driven member and said rectilinearmotion imparting member or said rotary motion imparting ,member, therebycausing said driven member and hence said specimen holder to move inunison with said rectilinear motion imparting member or said rotarymotion imparting member.

2. A specimen positioning device as set forth in claim 1 furthercomprising a. means for causing said rectilinear motion imparting memberand said rotary motion imparting member to rotate in unison with eachother about an axis other than the axis of said rotary motion impartingmember, thereby causing said driven member and hence said specimenholder to tilt.

3. A specimen positioning device as set forth in claim 1 wherein on theside surfaces of said rectilinearmotion imparting member and said rotarymotion imparting member in opposed relation with said driven disk arefixed members made of semiconductive ferroelectric material.

1. A specimen positioning device for an electron microscope or the likecomprising a. means for supporting a specimen; b. a driven member into acenter opening of which is fitted said specimen supporting means; c. arectilinear motion imparting member disposed in closely spaced apartrelation with said driven member on one side thereof; d. a rotary motionimparting member disposed in closely spaced apart relation with saiddriven member on the other side thereof; e. means drivingly coupled tosaid rectilinear motion imparting member for causing the fine motionthereof; f. means drivingly Coupled to said rotary motion impartingmember for causing the rotation thereof; and g. a voltage source oneterminal of which is connected to said driven member and the otherterminal of which is selectively connected through a switch to either ofsaid rectilinear motion imparting mechanism or said rotary motionimparting mechanism so that Coulomb electrostatic attraction is producedbetween said driven member and said rectilinear motion imparting memberor said rotary motion imparting member, thereby causing said drivenmember and hence said specimen holder to move in unison with saidrectilinear motion imparting member or said rotary motion impartingmember.
 2. A specimen positioning device as set forth in claim 1 furthercomprising a. means for causing said rectilinear motion imparting memberand said rotary motion imparting member to rotate in unison with eachother about an axis other than the axis of said rotary motion impartingmember, thereby causing said driven member and hence said specimenholder to tilt.
 3. A specimen positioning device as set forth in claim 1wherein on the side surfaces of said rectilinear motion imparting memberand said rotary motion imparting member in opposed relation with saiddriven disk are fixed members made of semiconductive ferroelectricmaterial.